(a) Field of Disclosure
The present disclosure relates to a trans inductor and a power converter using the same, and more particularly, to a trans inductor and a power converter that improve system efficiency of eco-friendly vehicles such as a plug-in hybrid vehicle and an electric vehicle.
(b) Description of the Related Art
Recently, the emergence of global environmental problems has created an interest in eco-friendly vehicles. In particular, an increase in efficiency of an inverter that directly influences fuel efficiency has become a significant issue and a high-voltage direct current to direct current (DC-DC) converter (HDC) that boost a battery voltage to enhance a voltage input to an inverter to thereby improve efficiency of the inverter has been researched. Generally, an eco-friendly vehicle using an electric motor as a power source, (e.g., a plug-in hybrid vehicle or an electric vehicle) includes a battery as a power source of the electric motor, an inverter configured to convert output of the battery to drive the electric motor disposed between the battery and the electric motor and the HDC configured to boost a battery voltage to improve a voltage input to the inverter disposed between the battery and the inverter. For example, to enhance inverter efficiency for fuel efficiency improvement of a vehicle, an eco-friendly vehicle uses a battery boosting converter called an High-Voltage DC-DC converter (HDC to increase an inverter input voltage to reduce an input current.
In particular, a boosting converter (e.g., an HDC) uses a bi-directional buck-boost converter. Accordingly, a representative component that influences HDC performance is an inductor that determines ripple current. Examples of an inductor used in a conventional buck-boost converter include a general inductor, an interleave inductor and a trans inductor. Typically, a general inductor allows ripple current flowing in a smoothing capacitor (e.g., an inverter input capacitor) to increase and therefor a capacity of a capacitor is increased. Additionally, the size or costs also increase. An interleave inductor provides for a reduction in ripple current that flows into a capacitor to be reduced by half, however, ripple current that flows in an HDC converter module increases and the loss also increases.
Generally, a trans inductor uses ferrite as a material of a core thereof. For example, in a vehicle system that instantaneously generates high current, when a core formed of ferrite is used the core is saturated due to generation of high peak current and unique properties of a magnetic substance may be lost. When a conventional inductor is used in a power converter or the like to instantly generate a high current, high peak current is generated in a switching device (IGBT). Accordingly a capacitor with high capacitance is required due to high ripple current or a core is saturated and the unique properties of a magnetic substance are diminished.
FIG. 1 is an exemplary diagram illustrating a structure of a power converter using a general inductor according to the related art. FIG. 2 is an exemplary diagram illustrating a structure of a power converter using an interleave inductor according to the related art. FIG. 3 is an exemplary diagram illustrating a structure of a power converter using a ferrite core-type trans inductor according to the related art. FIGS. 1 to 3 illustrate exemplary structures for power conversion of a battery used as a power source of an electric motor for eco-friendly vehicles and illustrate connection states of an HDC including inductors 2, 12, and 22 and HDC converter modules 3, 13, and 23, batteries 1, 11, and 21, smoothing capacitors 4, 14, and 24, and inverter power modules 5, 15, and 25.
In particular, the power converter of FIG. 1 uses the general inductor 2 and a circuit structure except for an inductor is the same as the power converters of FIGS. 2 and 3. The ripple current that flows in the smoothing capacitor 4 doubles compared with the interleave inductor 12 and the ferrite core-type trans inductor 22 and capacitance is required to double to achieve an equivalent performance. In other words, when a general inductor is used in an HDC inductor of a power converter, the high-peak current is generated as high current flows. Accordingly, capacitance is required to increase and high-peak current generates high noise which reduces electromagnetic waves of vehicles and the lifetime of components.
Further, when the power converter of FIG. 2 uses the interleave inductor 12, capacitance of the smoothing capacitor 14 at an inverter input side may be reduced. However, high-peak current flows in the HDC converter module 13 which increases switching loss and noise and the electromagnetic waves of vehicles and lifetime of the components are adversely affected. As shown in the power converter of FIG. 3 the ferrite core-type trans inductor 22 are used when high current is instantly generated and as an inductor core is saturated the inductance is reduced. In other words, the current is abruptly increased in a switch device.
The above information disclosed in this section is merely for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.